Why the Path Forward for Energy Storage Starts with Carbon

An ultracapacitor can be made from many materials and come in many different shapes and sizes. However, there are three main commercial offerings of capacitor energy storage (Symmetrical EDLC, Asymmetrical, and LiC) each with its own unique design and application. Yet as you read through the pros and cons below, one version stands out as the proven technology for the markets it serves.

Symmetrical EDLC: Also known as an ultracapacitor or Double Layer Capacitor, is two metal plates coated in activated carbon and then immersed in an electrolyte and isolated from each other by a separator. When you add a voltage (such as when charging) an electric field develops, which is how these ultracapacitors store energy.

  • Double-layer carbon capacitors are currently in high volume and a number of manufacturers are expanding production to meet global demand. See our recent release announcing the opening of our second manufacturing facility in the US. Demand is driven by the effectiveness of the double-layer carbon capacitor design within the transportation sector. Its high power and energy density, wider temperature range, and lower cost make the technology ideal for automotive and bus use.

Asymmetrical: a capacitor with two different electrodes, often referred to as a hybrid capacitor.

  • Asymmetrical capacitors have a low production rate with only a small handful of manufacturers and are not likely to see an increase in volume in the near future. While they have higher energy density than a traditional ultracapacitor, they have a much higher ESR or equivalent series resistance, resulting in a considerably lower power density. Also, due to its battery portion of the electrode, it has a lower cycle life (typically less than 20k cycles), a slower charge rate, and heavier weight.

LiC: functions primarily as an asymmetrical capacitor, however it has a lithium material embedded into the carbon electrodes.

  • The jury is still out on lithium-ion capacitors, or LiC. While they have the potential for major applications, there is very little production and no high volume. A LiC costs less per unit of energy, has higher energy density, however its power and cycle life are mediocre.

It’s clear that symmetrical double-layer carbon capacitors are paving the path forward for advancing energy storage by allowing for high duty cycle and a sustained high current throughput – an integral factor to energy efficiency and achieving the optimum level of energy regeneration. Two primary reasons for this productivity are a higher thermal capacity and more efficient packing of cells and modules. The double-layer design allows a great amount of energy/power through the system with the lowest amount of heat generation as possible, with the ability to dissipate that heat quickly.

As new technologies are investigated, thermal capacity remains the key to energy efficiency no matter the type of capacitor. Improved packaging methods, such as in our iMOD X-Series™, ensures even aging of the cells to create a longer lasting, more reliable product.
- Questions or comments? Feel free to send me an email (CHall@ioxus.com) or reach me on Twitter at the @Ioxushandle.

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  • uSTART® Lead-Free Replacement for Truck Batteries

    ONEONTA, N.Y.Jan. 9, 2019 /PRNewswire/ -- Ioxus uSTART® has received two fleet industry awards for sustainability by eliminating lead-acid batteries with its ultracapacitor-based, drop-in battery replacement.

    "With uSTART, fleets not only realize the benefits of improved starting reliability, there are equally important and real sustainability improvements from lead waste reduction," said Chad Hall, executive vice president and co-founder of Ioxus. "By replacing one of the batteries on a vehicle with a uSTART module, up to 15 fewer batteries are needed over the lifetime of the vehicle. This translates into 1,000 pounds of lead that will never need to be disposed of or allowed to affect groundwater."

    EU legislation on batteries is embodied in the European Battery Directive.  Its objective is to contribute to the preservation and improvement of environmental quality by minimizing the negative impact of batteries and battery waste.  As these preservation efforts expand, sustainable technologies develop to manage and mitigate these risks.

    Replacing a lead-acid battery with uSTART in a typical commercial vehicle creates measurable environmental benefits:

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